Container filling on an industrial scale is usually performed by automatic filling machines which are capable to repeatedly dispense with high accuracy a predetermined amount of flowable material into individual containers. Commercially available automatic filling machines normally comprise a conveyor belt advancing open top empty containers in a serial order through a filling station and subsequently through a capping station for sealing the containers. For applications where the containers are processed one by one, the filling station comprises a single fluid dispensing nozzle operating in a timed relationship with the containers feed rate. The nozzle comprises an elongated and vertically disposed fluid supply conduit with a discharge port at its lower end. The fluid feed to the supply conduit is achieved through a lateral inlet port located in proximity to the upper end of the supply conduit. The fluid flow through the supply conduit is controlled by a simple valve mechanism for opening or closing the discharge port. The valve mechanism includes a movable closure member coupled to an elongated actuating rod mounted for linear movement within the supply conduit. A pneumatic piston-cylinder assembly supported on the supply conduit selectively displaces the closure member, by the intermediary of the actuating rod, between valve closed and valve opened positions.
The first step of the container filling cycle consists of lowering the filling nozzle within the container to bring the discharge port in proximity to the container bottom. The valve of the nozzle is opened to initiate the fluid delivery and simultaneously the nozzle is lifted out of the container at a rate corresponding to the rate at which the fluid level in the container rises, in order to prevent the lower end of the nozzle to be submerged in the accumulating fluid mass. When the predetermined amount of fluid has been delivered, the valve of the nozzle is closed, terminating the filling cycle.
It has been observed that during the valve closing at the end of the filling cycle, a spray or splasing of fluid may occur. The reason for such spraying has been traced to a very high fluid velocity which develops through the valve immediately before the fluid tight engagement between the closure member and the valve seat is achieved to completely interrupt the fluid flow. Such fluid spray which may also occur when the valve opens to initiate the fluid delivery is highly undesirable because fluid droplets may be projected outside the container necessitating an extensive cleaning of the filling machine. In addition, the fluid spray may project fluid on the outside surface of the container which renders the container unacceptable for further processing.